A simple and accurate method for determining wheat grain fructan content and average degree of polymerization

An improved method for the measurement of fructans in wheat grains is presented. A mild acid treatment is used for fructan hydrolysis, followed by analysis of the released glucose and fructose with high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Not only the amount of fructose set free from fructans but also the released glucose can be quantified accurately, allowing determination of the average degree of polymerization of fructans (DP(av)). Application of the mild acid treatment to different grain samples demonstrated that a correction should be made for the presence of sucrose and raffinose, but not for stachyose or higher raffinose oligosaccharides. The fructan content and DP(av) of spelt flour, wheat flour, and whole wheat flour were 0.6%, 1.2%, and 1.8% of the total weight and 4, 5, and 6, respectively. Validation experiments demonstrate that the proposed quantification method is accurate and repeatable and that also the DP(av) determination is precise.     

A simple method for generating daily rainfall data

In recent years, agricultural scientists have developed considerable interest in modeling and simulation of rainfall as new ways of analyzing rainfall data and assessing its impact on agriculture. Among the proposed methods, a combination of Markov chain and gamma distribution function is recognized as a simple approach and is demonstrated to be effective in generating daily rainfall data for many environments. Unfortunately, this method requires that many years of daily weather records be available for estimating the model parameters. Thus the availability of the weather data limits the applicability of the simulation method. When these model parameters are evaluated over time and at different places, however, certain general characteristics are revealed. First, the transitional probability of a wet day followed by a wet day tends to be greater but parallel to the transitional probability of a dry day followed by a wet day. This phenomenon leads to a linear relationship of the transitional probabilities to the fraction of wet days per month. Second, the beta parameter in a gamma distribution function, which is used to describe the amount of rainfall, is closely related to the amount of rain per wet day owing to the positive skewness of the rainfall distribution. Based on these relationships, a simple method is introduced, by which model parameters can be estimated from monthly summaries instead of from daily values. The suggested method, therefore, provides a convenient vehicle for applying weather simulation models to areas in which its use had been impossible because of the unavailability of long series of daily weather data.     

高矿化度土壤水分特征曲线及拟合模型适宜性

为分析高矿化度对土壤水分特征曲线的影响,以淡水及矿化度分别为30、100和250g/L的水样对土体进行饱水处理(简称TDS-F、TDS-30、TDS-100和TDS-250处理),测定脱湿过程的土壤水分特征曲线。结果显示,试验吸力变化过程中,各处理比水容量相近,局部存在差异:TDS-100及TDS-250处理土体对水分的吸持能力明显小于TDS-30及TDS-F处理。分析表明:TDS-30处理使土体中等孔隙体积变小、TDS-100处理使土体较小孔隙体积变小、TDS-250处理使土体较大孔隙体积变小,进而影响土壤水分特征曲线形态。利用RETC软件结合统计分析确定,TDS-F、TDS-30、TDS-100及TDS-250处理土壤水分特征曲线的最优拟合模型分别为:vanGenuchten-Mualem、Dual-porosity-Mualem、Lognormaldistribution-Mualem及Dual-porosity-Mualem模型;各处理最优模型的非饱和导水率模式均为Mualem模型;从机理上解释各拟合模型优劣还较为困难。研究结果为干旱区高矿化度土壤水、盐运移计算提供一定参考。     

A simple and inexpensive method for counting anaerobic bacteria

Abstract

A serum bottle method for counting anaerobic bacteria in soil is described.     

A simple method for quantitative determination of ATP in soil

A simple method to measure soil ATP by the luciferin-luciferase system is described. The ATP is extracted from the soil by vigorous shaking with a sulfuric acid-phosphate solution for 15 min. An aliquot of the soil suspension is neutralized with a Tris-EDTA solution and mixed with a special ATP releasing reagent (NRB). ATP is measured after a 10 s exposure to the NRB reagent, followed by addition of luciferin-luciferase and integration over 10 s in a Lumacounter M 2080. The ATP content in soils which had been stored at 5°C for 90 days and then incubated at 25°C for 5 days, ranged from 0.37 to 7.52 μg ATP g^?1 dry wt, with standard deviations less than 10%. There was a close (r = 0.96) linear relationship between ATP content and biomass C determinated by fumigation for this group of soils. The soil biomass contained 4.2–7.1 μg ATP mg^?1 biomass C. The ATP content of the biomass declined during storage at 5°C for 210 days.     

A simple turbidimetric method for determination of exchangeable soil potassium

Abstract

It was found that sodium tetraphenylboron, NaB(C₆H₅)₄, can be used as a reagent for determination of K in acid sodium acetate extracts of soils. After extraction and filtration, sodium hydroxide and formaldehyde are added prior to the reagent to avoid interference of ammonium. At low concentrations of K in the extracts (<30 mg K/1) the white precipitate of potassium tetraphenylboron, KB(C₆H₅)₄, is colloidal and the concentration of K can be determined turbidimetrically with a simple instrument in the field or on the farm.     

A simple method for detection of lipolytic microorganisms in soils

Media selective for the isolation of bacteria, actinomycetes and fungi were amended with 0.1% sunflower oil emulsified with 0.01% Tween 80. Lipase-producing microorganisms produced clear zones on these media. When lipase-producing bacteria were cultured on a polycarbonate membrane laid on the selective medium for bacteria, clear zones were produced on the medium when the membrane along with bacteria was removed. The agar disc cut from the clear zone also produced a clear zone when placed on the fresh medium, indicating that clear zone formation is the result of the activity of extracellular lipases. The largest population of lipase-producing microorganisms in an agricultural soil was actinomycetes followed by bacteria and fungi. Ranging from 12 to 75% of bacteria, actinomycetes and fungi isolates from soils collected from three different locations were capable of producing lipases. In general, relatively small percentages of soil bacteria were lipase producers, and lipase producers were more common among soil actinomycetes and fungi. These three groups of microorganisms appear to be all important in decomposition of oils in organic matters in soils.     

A fast and simple method for classification of soil bacterial populations

A simple method is described for a rough classification of soil bacterial populations. The method makes use of a commercially available biochemical test system and the test results are analysed in a multivariate classification program on a microcomputer. The method was used for classification of bacteria from rape rhizosphere.     

A simple and inexpensive method for chromium speciation in soil extracts

Abstract

Chromium (Cr) appears in two stable forms in nature as Cr(III) and Cr(VI). Hexavalent chromium (CrO₄ ^2‐; Cr₂O₇ ^2‐) is very toxic and carcinogenic, while inorganic Cr(III), however, is essential for mammals. Only two methods, atomic absorption and inductively coupled plasma atomic emission (ICP) spectrometry, provide information on the total amount of Cr in a test solution. This is the reason that several efforts have been made with regard to Cr speciation. Either an acidic or a basic activated aluminum oxide and a reversed phase C‐18 column or an ion exchanger column are used for the separation of chromium(III) from chromium(VI) in FIA and HPLC analyses. In our experiments, acidic‐activated aluminum oxide was used for separation. This alumina was placed into a silicon tube and connected to an ICP spectrometer between the nebulizer and peristaltic pump. The average grain size of the alumina was large enough that the solution could be pumped through the micro column. Acidic‐activated aluminum oxide in the 2.0 to 8.0 pH range adsorbs the chromate anion but not the Cr(III) cation. During this stage, the Cr(III) content of a sample is measurable. The adsorbed chromate can be eluted with a strong acid. The height or area of the elution peak can be used for the calibration of Cr(VI). Detection limits of 4 μg/kg and 0.5 μg/kg were obtained for Cr(III) and Cr(VI), respectively. The effects of sulphate and phosphate anions on the surface of the alumina on chromate adsorption were also evaluated. This method was used for the measurement of Cr(VI) concentration by 0.01M CaCl₂ extraction of soil.     

A simple method for assessing leaching risk of bacteria through soils

Abstract. Bacterial contamination of water is a problem worldwide and is often acute in developing countries where human and animal waste is disposed of on land for use as fertilizer or because of poorly developed sanitation systems. Studying leaching risk through soils is difficult when no suitable microbiological laboratory is available. A method using the movement of ZnO particles through soils as a surrogate for studying bacteria directly was tested. ZnO particles with a similar size to bacteria can readily be detected by chemical analysis. For a range of nine different soil textures, leaching rates of ZnO particles under near saturated conditions were significantly correlated with leaching rates of Escherichia coli cells ( P =0.013). For both ZnO and E. coli , leaching was generally greatest through fine textured soils.     

A simple and rapid method for labelling earthworms with N and C

A simple, rapid and cost-effective laboratory method was developed for labelling soil-feeding earthworms simultaneously with ¹⁵N and ¹³C. The method circumvents the production of labelled plant material and can be adapted to devise pulse-labelling or long-term labelling protocols. Soil was amended with ¹⁵NH₄⁺ and incubated for 7 days. Then, U-¹³C-glucose was added and endogeic earthworms, Aporrectodea caliginosa (Oligochaeta: Lumbricidae), were provided individually with 4 g of this pre-incubated soil. The labelling period was 4 days. The labelling efficiency (percentage of tracer retained in earthworm tissues) was estimated to be 15.8% for ¹⁵N and 10.3% for ¹³C. The loss of ¹⁵N and ¹³C label from tissue and mucus was traced for 21 days post-labelling. Label loss from mucus was best described by a two-term exponential function, whereas the label loss in body tissue followed a single-term exponential function. Half-life estimates for the ¹⁵N and ¹³C tracers in body tissue were 16 and 37 days, respectively.     

药雾浓度沉降曲线拟合方法的试验)(简报)

为了解温室大棚等密闭空间喷雾后的药雾浓度衰减规律,该文以常温烟雾机在棚室中喷雾后的药雾浓度为研究对象,针对D.K.Giles的药雾浓度沉降曲线拟合方法进行了改进,相对于老方法将采样时间段内获得的药雾浓度值置于中间时刻点进行拟合,新方法将该值分别对应于该时间段内3个不同时刻点进行拟合分析。新方法同时还建立了比较曲线拟合优劣的一种工程判据,据此判据得出在5 min的采样时间段条件下,将采样数据作为该采样时间段内第2 min时刻点的药雾浓度值,然后进行拟合,所得药物总质量和实际施用药物总质量相对误差最小,仅为1.6%。研究还表明,在浓度沉降过程中,某一采样周期内的浓度值主要由这一时间段的前段采样所贡献。     

A simple digital imaging method for estimating black-soil organic matter under visible spectrum

Soil organic matter (SOM) plays a key role in soil, and is used to determine soil quality. Conventional soil property analysis is relatively slow, expensive and laborious. Although using a spectrometer can quickly assess a large amount of organic matter content, it is an expensive, complex and undefined process. This article presents a potential simple method for estimating black-SOM that uses a digital camera that is cheaper and easier to operate than a spectrometer. RGB (red, green and blue) image-intensity values of the soil from a digital camera were measured, to research the relationship between black-SOM and RGB. The results show the red image-intensity values provide the greatest correlation with SOM, with a correlation coefficient (r) reaching 0.73. A comparison with spectrometer results for SOM predictions shows that the best prediction result for the digital camera (R² = 0.72, root-mean-square error [RMSE] = 0.40) is slightly better than the spectrometer (R² = 0.65, RMSE = 0.45) at certain band points. Thus, a low-cost digital camera that is easy to operate can be used as an alternative tool for the rapid and accurate estimation of black-SOM content.     

A simple method for estimating nitrate removal from floodwaters in river marginal wetlands

Abstract. Soil cores from river marginal wetlands in the UK, France and Ireland, sampled and contained within PVC piping, were flooded with nitrate-N enriched water. Half of the cores were sterilized prior to flooding to destroy the denitrifying bacteria. The change in nitrate-N concentration in the floodwater was measured over time. It is argued that the observed nitrate depletion rates (from 0.4 to 2.3 kg/ha per day) may be identified With microbially-mediated denitrification. The results show the method to be a simple and direct procedure for the assessment of spatial variation in nitrate-sink capacity. The depth of the denitrifying layer at the soil-water interface was confirmed to be of the order of a few mm.     

A simple method for the estimation of potential primary pasture productivity over Mozambique

Pasture production not only depends on precipitation amount and distribution patterns, but also on soil type and evaporative demand. The simulation model of Rose et al., developed using improved pastures, is one that accounts for these factors and also takes into account the effect of fertilizer levels on production. From this a simplified model is proposed for Mozambique using as inputs annual precipitation, annual potential evapotranspiration and soil moisture storage capacity. The model is applicable only under negligible soil slope and no bush or tree cover, but can be adapted to varying phosphate fertilizer levels. Estimates from this proposed model show close agreement with experimental data from cleared natural pastures in Zimbabwe and with improved pastures of Townsville stylo in Australia under high phosphate fertilizer levels.     

A simple laboratory infiltration method for measuring the tendency of soils to crust

Abstract. Rainfall simulation experiments give an indication of the tendency of soils to crust or seal but are time-consuming and require several kilograms of soil per sample. We developed a laboratory infiltration method that is less time-consuming than rainfall simulation and uses less than 40 g of soil. The method involves the leaching of an agitated 1:5 soil/water suspension through a packed soil column, which simulates the crusting process. The preparation of a dispersed soil suspension is a key feature of the method as it simulates disturbance of a soil surface by rain. This laboratory infiltration method was performed on sandy, granite-derived soils from annually burnt as well as unburnt plots in the Kruger National Park, South Africa and gave results which correlated strongly with results from rainfall simulation experiments on the same soils. We suggest that this new method may be useful for assessing the effect of different land management practices on the tendency of soils to crust.     

基于地表昼夜温差的平原区土壤质地模糊聚类与预测制图

The use of landscape covariates to estimate soil properties is not suitable for the areas of low relief due to the high variability of soil properties in similar topographic and vegetation conditions.A new method was implemented to map regional soil texture (in terms of sand,silt and clay contents) by hypothesizing that the change in the land surface diurnal temperature difference (DTD) is related to soil texture in case of a relatively homogeneous rainfall input.To examine this hypothesis,the DTDs from moderate resolution imagine spectroradiometer (MODIS) during a selected time period,i.e.,after a heavy rainfall between autumn harvest and autumn sowing,were classified using fuzzy-c-means (FCM) clustering.Six classes were generated,and for each class,the sand (> 0.05 mm),silt (0.002-0.05 mm) and clay (< 0.002 mm) contents at the location of maximum membership value were considered as the typical values of that class.A weighted average model was then used to digitally map soil texture.The results showed that the predicted map quite accurately reflected the regional soil variation.A validation dataset produced estimates of error for the predicted maps of sand,silt and clay contents at root mean of squared error values of 8.4%,7.8% and 2.3%,respectively,which is satisfactory in a practical context.This study thus provided a methodology that can help improve the accuracy and efficiency of soil texture mapping in plain areas using easily available data sources.     

A simple and precise method for total chlorophyll analysis in tropical foliage plants 1

Methods currently in use for total chlorophyll analysis of plant tissue were reviewed. Storage of leaf tissue before analysis, filtration methods during analysis and extract longevity were investigated. The final procedure includes the use of leaf area cores and extraction with 100% acetone with results reported by area and oven dry weight. A simple and precise composite method was adopted.     

A miniaturized method for fast,simple, and sensitive pesticide analysis in soils

Journal of Soils and Sediments - Organochlorine pesticides (OCPs) like lindane and DDT have been used extensively after World War II until the 1990s. Still, residues of these pesticides can be...     

A relatively simple scaling method for describing the unsaturated hydraulic functions of stony soils

Few if any methods exist to estimate the effects of stone content (stoniness) on the unsaturated soil hydraulic properties. A relatively simple scaling method is presented to estimate the hydraulic conductivity of unsaturated stony soils having different stone contents. A key assumption of the method is that van Genuchten's water retention parameters α and n of the fine soil fraction are the same as those of the stony soil. The method further assumes a linearly decreasing relationship between the saturated hydraulic conductivity and the stone content, based on previous numerical simulations. Using the proposed method, it is possible to calculate the hydraulic conductivity of unsaturated stony soils, knowing the saturated hydraulic conductivity of the fine soil fraction, the retention curve of the fine soil fraction, and the particular stoniness of the soil.